This invention relates to the use of D-tagatose, such as in a chewing gum, to combat the adverse health, physical, cosmetic and environmental effects of biofilms.
Biofilms are conglomerations of microorganisms that consist of one or more species of bacteria, fungi, algae, and protozoa, singly or as a mixture, in which the participants adhere together in an aqueous environment to form a film attached to surfaces or in free standing suspension. Secreting a glue-like substance not secreted as single cells in suspension, the organisms constituting biofilms can anchor to a wide variety of materials by extruding sisal-like filament attachments. Biological, organic, and inorganic surfaces are subject to biofilm formation. These surfaces include teeth, gums, human and animal blood vessels, medical implant materials, soil particles, metals, and plastics. Upon forming a biofilm, the participating organisms alter their morphology, behavior, and metabolism. Virtually any surface in contact with water is subject to the development of adhering biofilms. Alternatively, microorganisms can form biofilms as floating conglomerates similarly altering their characteristics.
When single species form biofilms, they differentiate, effectively becoming a multi-task community. In many instances, biofilms cause problems interfering with the normal operation, perhaps causing failure, of natural and artificial systems. The effects range from clogging capillary blood vessels in the circulatory system or brain that may lead to stroke, to causing prosthetic valve endocarditis, to constricting the effective diameter of stints surgically implanted to increase blood flow, to creating plaque and causing gingivitis in human or animal mouths, to clogging tubes and other plumbing in industrial equipment, to causing loss of efficiency in heat exchange systems. The total annual cost of these adverse consequences of biofilms runs into the billions of dollars.
More economic and specific measures to control biofilms are required. Many of the normal bio-control products, such as anti-microbials and disinfectants, are inadequate in combating many instances of biofilm infestation.
The U.S. Public Health Service Communicable Disease Center states that up to 65% of bacterial infections in humans are biofilms in nature. Furthermore, microorganisms that form biofilms then change their characteristics, sometimes drastically, such that doses of antibiotics which normally kill the organisms in suspended cultures are completely ineffective against the same microorganisms when the organisms are in attached or conglomerate biofilm form.
Biofilms play a key role in dental disease. Bacterial activity of over 500 different bacteria has been implicated in human dental plaque and in caries [Kolenbrander P. E., “Oral microbial communities: biofilms, interactions, and genetic systems”, Annu. Rev. Microbiol., 54:413–437, 2000]. Adhesion of the bacteria to each other (intraspecies) and to other bacterial species (interspecies), as well as to oral surfaces, is one of the major factors leading to dental plaque and to caries and periodontal diseases.
Streptococci and actinomycetes are the major initial colonizers in forming dental biofilms. Their adhesion to the pellicle of salivary glycoproteins on tooth surfaces appears to be the first step in the formation of dental plaque [Kolenbrander P. E., “Oral microbial communities: biofilms, interactions, and genetic systems”, Annu. Rev. Microbiol., 54:413–437, 2000]. Microorganisms that progressively accumulate thereafter, mostly gram negative anaerobic bacteria, in the gingival crevice area are the late colonizers and are believed to play a central role in the initiation and progression of periodontal diseases [Moore W. E., and Moore L. V., “The bacteria of periodontal diseases”, Periodontol 2000, 5:66–77, 1994]. In this accumulative step, the bacteria coaggregate. The stability of plaque containing growing bacteria is a result of bacterial adhesion to the acquired pellicle, and, most importantly, of interspecies adhesion, the phenomenon of coaggregation. The bacterial species present in dental plaque are heterogeneous and they change progressively as the clinical condition goes from normal health through gingivitis to advanced stages of periodontitis. Fusobacterium nucleatum is the principal and most frequent cause of gingival inflammation that may initiate periodontal diseases, and it is also most commonly the predominant pathogen in subsequent periodontal destruction [Moore W. E., and Moore L. V., “The bacteria of periodontal diseases”, Periodontol 2000, 5:66–77, 1994; Bolstad A. I., Jensen H. B., and Bakken V., “Taxonomy, biology, and periodontal aspects of Fusobacterium nucleatum”, Clin. Microbiol. Rev., 9:55–71, 1996]. F. nucleatum plays a central role in providing physical bridges that mediate coaggregation of cells, thereby promoting anaerobic microenvironments that protect the coaggregating strict anaerobes [Kolenbrander P. E., “Oral microbial communities: biofilms, interactions, and genetic systems”, Annu. Rev. Microbiol., 54:413–437, 2000; Kolenbrander P. E., and London J., “Adhere today, here tomorrow: oral bacterial adherence”, J. Bacteriol., 175:3247–3252, 1993]. F. nucleatum coaggregates with many putative periodontal pathogens, such as Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Prevotella intermedius, and certain species of Treponema, Eubacterium, and Selenomonas. 
These periodontopathogens are also the prominent contributors to the formation of volatile sulfur compounds (VSC), the major components of halitosis [Quirynen M., Van Eldere J., Pauwels M., Bollen C. M., and van Steenberghe D., “In vitro volatile sulfur compound production of oral bacteria in different culture media”, Quintessence Int., 30:351–356, 1999; Waler S. M., “On the transformation of sulfur-containing amino acids and peptides to volatile sulfur compounds (VSC) in the human mouth”, Eur. J. Oral Sci., 105:534–537, 1997]. Unlike P. gingivalis that is usually absent in healthy gingival sulci, F. nucleatum is one of the dominant species not only in the lesions of periodontitis but also in gingivitis lesions and healthy gingival sites.
Dental plaque also contributes to tooth discoloration and to gingival irritation and subsequent periodontal disease. Current studies suggest that the periodontal diseases may trigger blood clots which can cause a heart attack or stroke [Wu T., Trevisan M., Genco R. J., Falkner K. L., Dorn J. P., and Sempos C. T., “Examination of the relation between periodontal health status and cardiovascular risk factors: serum total and high density lipoprotein cholesterol, C-reactive protein, and plasma fibrinogen”, Am. J. Epidemiol., 151:273–282, 2000]. Once plaque bacteria enter the bloodstream through ulcerations in the gums, they may cause clots that then impede blood flow. The adhesions among bacteria and between or among bacteria and blood cells may be the mechanism. Hence, controlling plaque is expected to reduce the risk of developing such diseases.
Streptococcus can coaggregate and form biofilms on prosthetic heart valves. When heart valves are replaced, despite normal surgical care, endocarditis (infection of the valve) not infrequently occurs. A biofilm then develops, impairing the functioning of the valve. The principal treatment is replacement of the infected valve. While intravenous antimicrobial treatment has been attempted, it has largely been unsuccessful because of the protection the biofilm affords against penetration to the interior microbial cells that maintain the infection. When endocarditis occurs, some 70% of the time the results are fatal to the patient.
D-Galactose is known [Kolenbrander P. E., and Andersen R. N., “Inhibition of coaggregation between Fusobacterium nucleatum and Porphyromonas (Bacteroides) gingivalis by lactose and related sugars”, Infect. Immun., 57:3204–3209, 1989; Shaniztki B., Hurwitz D., Smorodinsky N., Ganeshkumar N., and Weiss E. I., “Identification of a Fusobacterium nucleatum PK1594 galactose-binding adhesion which mediates coaggregation with periopathogenic bacteria and hemagglutination”, Infect. Immun., 65:5231–5237, 1997] to reverse the coaggregations of oral bacteria that would otherwise form dental plaque. This property constitutes a distinct advantage if incorporated into toothpaste or mouthwash. D-Galactose, however, is low in the hygroscopicity required for toothpaste, is not sweet-tasting and does not have good mouthfeel.
D-Tagatose has been under development as a low-calorie, full-bulk sweetener for use in foods. It has also been under development for use in cosmetics, such as toothpaste and mouthwash. Generally Recognized As Safe (GRAS) status has been obtained for these uses.